1. Field of the Invention
The present invention relates to a structure of a self-locking (single-acting) type push-button switch and more particular to a structure of a push-button switch having a reset mechanism for canceling a locked state.
2. Description of the Prior Art
According to a conventional push-button switch of a self-locking (single-acting) type, an operating portion (a slide member) is locked in a predetermined position when depressed first and is unlocked and returns to its initial position when depressed next. If another switch is operated in a locked state (circuit ON) of the push-button switch, for example in case of simultaneous locking (circuit ON), there occurs a circuit-related problem. Due to this problem, when the push-button switch must be returned to its reset position (initial position), it is necessary that the operating portion which has first been locked in its locking position be canceled its locked state by a second depressing operation.
As other push-button switches than the self-locking type there are known interlocking type push-button switches and interlocking/single-acting type push-button switches (when one operating portion, out of two operating portions, is in an unlocked state, the other operating portion performs a single-acting operation involving repeated locking and unlocking operations, and when one operating portion is in a locked state, the other operating portion performs an interlocking operation in which the other operating portion cancels the locked state of the locked one operating portion and the other operating portion itself is locked) However, these known types require the use of two or more push-button switches, resulting in complicated structures and increase of cost.
As a self-locking type push-button switch having a reset mechanism for canceling a locked state there is known a self-return type push-button switch using solenoid. In this self-return type push-button switch, the solenoid is energized with an operating portion locked in a locked position, so that the locked state of the locking portion, which is locked mechanically, is cancelled by utilizing an attractive force of the solenoid.
In the above structure of the conventional self-lock type push-button switch, however, for returning the operating portion which has first been locked in its locking position to its reset position (the initial position), it is necessary to perform the second depressing operation. Therefore, when the locked state of this push-button switch must be canceled at the time of operating another switch, the associated operation has so far been troublesome.
In the self-return type push-button switch using solenoid, the provision of solenoid is required separately for unlocking the operating portion, thus giving rise to the problem that the structure becomes complicated and the cost increases.